Intermetallic compound materials

ABSTRACT

An intermetallic compound material based on tri-nickel aluminide which may be produced by standard vacuum melting techniques, is composed of a first group of constituents in which the nickel is partly replaced by at least one of the elements chromium, cobalt, molybdenum and tungsten and a second group of constituents in which the aluminium is partly replaced by hafnium and by at least one of the elements titanium, niobium and tantalum, the material containing the constituents in the proportions, by atomic percentage, FIRST GROUP OF CONSTITUENTS 72 TO 83 SECOND GROUP OF CONSTITUENTS 17 TO 28 One preferred composition of the intermetallic compound material contains elements of the said first and second groups in the following ranges specified below, in atomic per cent,   The intermetallic compound material may contain carbon, boron, and zirconium as trace elements.

United States Patent [191 Restall et a1.

1 1 Nov. 25, 1975 1 1 INTERMETALLIC COMPOUND MATERIALS [75] Inventors: James Edward Restall, Frimley; Michael James Douglas Weaver, Fleet, both of England [73] Assignee: National Research Development Corporation, London, England 22 Filed: Jan. 10, 1974 211 App1.No :432,392

Related U.S. Application Data [63] Continuation-impart of Ser. No. 256,026, May 23,

[30] Foreign Application Priority Data May 26, 1971 United Kingdom 17150/71 Jan. 12, 1973 United Kingdom 1676/73 [52] U.S. Cl. 75/171; 75/170; 148/32;

148/325 [51]. Int. Cl. C22C 19/05 [58] Field of Search 75/171, 170; 148/32, 32.5

[56] References Cited UNITED STATES PATENTS 3,617,397 11/1971 Maxwell 75/170 3,767,479 10/1973 Tarshis 75/171 FOREIGN PATENTS OR APPLICATIONS 1,01 1,785 12/1965 United Kingdom 1,019,679 2/1966 United Kingdom 1,036,148 7/1966 United Kingdom 1,065,770 4/1967 United Kingdom 1,087,051 10/1967 United Kingdom Primary E.raminer-R. Dean Attorney, Agent, or FirmCushman, Darby &

Cushman [57] ABSTRACT An intermetallic compound material based on trinickel aluminide which may be produced by standard vacuum melting techniques, is composed of a first group of constituents in which the nickel is partly replaced by at least one of the elements chromium, cobalt, molybdenum and tungsten and a second group of constituents in which the aluminium is partly replaced by hafnium and by at least one'of the elements titanium, niobium and tantalum, the material containing the constituents in the proportions, by atomic percentage,

first group of constituents 72 to 83 second group of constituents 17 to 28 One preferred composition of the intermetallic compound material contains elements of the said first and second groups in the following ranges specified below, in atomic per cent,

The intermetallic compound material may contain carbon, boron, and zirconium as trace elements.

4 Claims, No Drawings INTERMETALLIC COMPOUND MATERIALS This application is a continuation-in-part of our copending application Ser. No. 256,026 filed May 23, 1972 for lntermetallic Compound Materials.

This invention relates to intermetallic compound materials based on tri-nickel aluminide (Ni A1) and which include hafnium.

The majority of high temperature structural components currently used in gas turbine aero engines are made from nickel-base alloys strengthened primarily by the precipitation of Ni Al (gamma-prime) throughout the nickel (gamma) matrix. During recent years, the strengths of such alloys have been improved by increasing the stability and volume fraction of the gammaprime precipitate through the introduction of relatively large quantities of elements such as tungsten, molybdenum, tantalum, niobium and titanium. This has involved reduction of the nickel and chromium content, the strength improvements thus being obtained at the expense of corrosion resistance. It is known that in addition to its precipitation strengthening role, the gamma-prime phase present in commercial precipitationhardened nickel-base alloys has good corrosion resistance at high temperatures.

Binary Ni A1 has little worthwhile high temperature strength and is fairly brittle but alloys based on Ni Al containing additional alloying elements can combine the high corrosion resistance of Ni Al with the strength and ductilities of modern precipitation-hardened nickel-base alloys at higher temperatures than the latter can withstand.

An intermetallic compound material based on trinickel aluminide according to the invention is composed of a first group of constituents in which the nickel is partly replaced by at least one of the elements chromium, cobalt, molybdenum, and tungsten and a second group of constituents in which the aluminum is partly replaced by hafnium and by at least one of the elements titanium, niobium and tantalum, the material containing the constituents in the proportions by atomic percentage,

72 to 83 17 to 28 First group of constituents Second group of constituents Preferably the constituents are in the following ranges (specified in atomic per cent):-

Nickcl 60 to 80 Aluminium 12 to 26 Chromium 2 to 6 Titanium to 12 Cobalt 0 to 12 Niobium 0 to 6 Molybdenum 0 to 3 Tantalum 0 to 6 Tungsten 0 to 3 Hafnium Up to 6 Nickel Balance Aluminium 16.5 Carbon Chro- 3.5 Hafnium 0.5 Boron 0.05

mium

Cobalt 7.1 Tantalum 3.6 Zirconium 0.05 Tungsten 0.9

This composition is representative of those believed to give good combinations of desirable properties, but is not intended to be exclusive. The composition when conventionally cast using standard vacuum casting procedures, has the following properties:-

TABLE I Tensile Properties Test UTS (tsi) 7: Elongation temperature C TABLE I1 Creep Properties Test conditions Life (hours) 71 Elongation 4 tsi 1100C 76 6 8 tsi 1000C 10 20 tsi 900C 171 6 TABLE 111 Oxidation Properties Total weight gain after Tri-nickel aluminide exists only over a very narrow range in the Ni-Al phase diagram, and it is difficult to cast a component with a single phase structure. All the compositions according to the invention therefore are likely to contain, both in the conventionally cast condition and after unidirectional solidification, small quantities of nickel (gamma) and Ni-Al (beta) type phase, either separately or together. Metal carbides and borides are also likely to be present.

1 claim:

1. In an intermetallic compound material based on trinickel aluminide consisting essentially of constituents in proportion by atomic percent:

first constituents 72-83% wherein the elements are present in the range, in atomic percent,

Nickel 60-80 Chromium 24,- cobalt 0-12 Molybdenum 0-3 Tungsten 0-3 second constituents 17-28% wherein the elements are present in the range, in atomic percent Aluminum 13-36 Titanium |2 Niobium -6 Tantalum 0-6 A. chromium about 3.5 cobalt about 7.1 tungsten about 0.9

B. aluminum about 16.5 hafnium about 0.5 tantalum about 3.6

and

carbon about 0.5

-contmued boron about 0.05 zirconium about 0.05 nickel balance.

3. An intermetallic compound material as claimed in claim 2 including carbon, boron and Zirc cnium as trace elements in proportions by atomic percentage,

Carbon 0.05 to 0.5 Boron 0.01 to 0.1 Zirconium 0.01 to O2 4. An intermetallic compound material as claimed in claim 1 including carbon, boron and zirconium as trace elements in proportions, by atomic percentage,

Carbon 0.05 to 0.5 Boron 0.01 to 0.1 Zirconium 0.01 to 0.2. 

1. IN AN INTERMETALLIC COMPOUND MATERIAL BASED ON TRINICKEL ALUMINIDE CONSISTING ESSENTIALLY OF CONSTITUENTS IN PROPORTION BY ATOMIC PERCENT: FIRST CONSTITUENTS 72-83% WHEREIN THE ELEMENTS ARE PRESENT IN THE RANGE, IN ATOMIC PERCENT,
 2. An intermetallic compound material based on trinickel aluminide consisting essentially of, atomic percentage:
 3. An intermetallic compound material as claimed in claim 2 including carbon, boron and zirconium as trace elements in proportions by atomic percentage,
 4. An intermetallic compound material as claimed in claim 1 including carbon, boron and zirconium as trace elements in proportions, by atomic percentage, 